closure lesson fix for returning on the same line as zip() declaration

[TomDeFrank]

The closure lesson as it stands can incorrectly fail.

It occurs if the student has their return statement on the same line as their zip() function declaration.

This fails:

function foo() {
  var bar;
  quux = 1;

  return function zip() {    
    var quux = 0;
    bar = true;
  };
}

This passes:

function foo() {
  var bar;
  quux = 1;

  function zip() {    
    var quux = 0;
    bar = true;
  };
  return zip;
}

By doing a regex match on scopeAsAscii for the string "return" you can accommodate both potential solutions.

Please let me know if you have any questions.